Welcome, Kayla,
You're a girl. That's all there is to it. I recommend you find a therapist (one that is familiar with gender issues, that person can help you drive it home to your parents). This might be easy to work out, just continue to tell your parents how you feel and suggest that maybe a therapist might help you get fixed is if you wish to be a happy boy. It's a small lie and a harmless one. The truth is just what Willow said. You're not actually broken, you're just in the wrong body. You need to bring out the real you, it's what's going to make you happy. You've found a family here, little sister of mine. Not only do we understand, but we're 100% on your side. You always have us to lean on when it gets to be too much. Don't be afraid to reach out and ask questions of any of us.
love,
-maggie